Rubber mixer



1952 c. F. SCHNUCK :rm. 2,615,

. RUBBER MIXER Filed July 31, 1950 2 SI-EETS--Sl-IEET. 1

Oct. 28, 1952 Filed July 31, 1950 c. F. SCHNUCK EI'AL 2,615,639

RUBBER uxxm 2 swans-sum 2 f m 34 a? l m Q m r q g Inventors "v W 44 W/ (Ittomegs Patented Oct. 28, 1952 RUBBER MIXER Carl F. Schnuck, North Haven, "and Oliver W.

Hooker, Woodbridge,-Conn., assignors to-Farrel- Birmingham Company, Incorporated, Ansonia, Conn., a corporation of Connecticut ApplicationJuly 31, 1950, Serial'No. 176,876

This invention relates to rubber mixers or masticators and more particularly to a rubber mixer of the Banbury type and is particularly concerned with the provision of a novel form of discharge door for the discharge openingat the bottom of the chamber of the mixer.

Rubber mixers of this type comprise what is usually referred to as a double cylindrical chamber in that the chamber consists of two cylinders placed side by side with their axes in parallel horizontal relation, the cylinders communicating with each other at their adjacent portions or at the portions lying between their axes. A rotor is provided in each of the cylinders, each of the rotors being provided with blades the tips of which approach closely the walls of the respective cylinders. The chamber formed by the two communicating cylinders is provided with a bottom discharge opening at the center of the chamber and extending lengthwise across the center, and to close this opening a sliding door is provided so that after a batch of rubber or other plastic material has been treated in the machine the door may be moved outwardlyto open position and allow the batch to drop by gravity from the chamber.

In the past this door has been formed at its lower portion to fit tightly against the sides of the openings in the cylinders and with curved upper surfaces forming a continuation of the inner surfaces of the cylinders, these upper surfaces fitting tightly against similarly shaped surfaces of the end walls of the chamber. These upper curved surfaces are not usually continued to a point but the door has been provided with a flat top which also is made to fit against similarly shaped surfaces in the end walls. Thus, the door must be formed to fit against the end plates or walls of the chamber upon three surfaces at each end and, in addition, it must fit the cylindrical walls at each side at its lower portion. This involves the fitting of five opposed surfaces and the maintenance of a tight fit during long operation of the device.

It will be understood that these devices are often operated under considerable pressure, the pressure being applied either by a forward plunger or floating weight mounted in the charging stack and it is, therefore, necessary that the door fit tightly at all engaging surfaces to prevent leakage of the material therethrough.

One object of the present invention is to provide a new and improved mixer or masticator for plastic materials.

A further object of the invention is to provide 2 Claims. (01.259-41) a mixer or masticator for plastic materials of the Banbury type having a bottom discharge opening and a novel form of door for closing this ,opening.

A still further object of the invention is to provide a mixer or masticator for plastic mateterials of the type described, the chamber of the mixer comprising a movable door or closure member having two fiat upper surfaces which meet in a straight line; these surfaces fitting tightly against correspondingly shaped surfaces provided upon the end walls of the chamber.

To these and other ends theinvention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a side elevational View of a mixer or masticator embodying our invention, some parts being broken away to show the interior mechanism; V

' Fig. 2 is a sectional view on line 22 of Fig. 1;

and

Fig. 3 is an enlarged sectional view similar to Fig. 2.

To illustrate a preferred embodiment of our invention, we have shown in the drawings a mixer or masticator comprising a chamber l0 having a charging stack II at the upper portion thereof, the charging stack being provided, with end walls l2 which are continued downwardly to formv the end walls or end plates for the chamber l0.

As shown the chamber is of the double cylindri'cal type consisting of the two cylinders 13 and M in each of which is mounted a bladed rotor l5. As will be seen from Figs. 2 and 3 of the drawings, the two cylinders communicate with each other at their adjacent portions so as toform a chamber of substantially double cy1indrical shape.

At the lower portion of the chamber and at the central portion thereof there is provided a discharge opening I6, this opening being closed by a door I! which'in this instance is slidably in the base portion 26 of the mixer. As the piston is thus fixed against longitudinal movement, it will be understood that introduction of fluid pressure upon one side or the other of the piston 23 will eifect movement of the cylinder l8 and door I! in opposite directions to open and closed positions as illustrated, for example, in United States patent to Banbury No. 1,523,387.

Heretofore, in machines of this character the end plates of the chamber at points adjacent the discharge opening have been provided with arcuate surfaces in continuation of the inner cylindrical surfaces of the chambers as shown by the dotted lines 28 and 29 of Fig. 3. These surfaces have been continued upwardly to a point adjacent the axes of the rotors and there connected by a fiat surface 30. Also the doors were similarly shaped, as they must fit tightly against the surfaces 28, 29 and 30 of the end plates and also against the two lateral edges of the opening [6 in order to effectively close the chamber.

In the present instance instead of forming curved surfaces at the upper sides of the door and at the lower portions of the end plates adjacent the discharge opening, we provide flat plane surfaces, these surfaces meeting in a straight line. To this end the end plates are provided with the straight edges 3| and 32 meeting at a straight line and the upper surfaces of the door I! comprise fiat plane surfaces 33 and 34 which meet in the line 35. It may be also noted that theline 35 which denotes the extreme upper surface of the door or closure member I! is considerably below the point 30 which has in the past been the upper surface of the door.

The two plane surfaces of the door may be given any slope desired depending upon conditions and the size of the mixer. The inclined angle between these surfaces may, for example, be from 90 to 105 or above or below these limits as desired. It will be understood, of course, that these surfaces must lie without or at least be tangent to the imaginary surfaces 28 and 29 so as to permit rotation of the rotor blades. As shown the surfaces lie slightly without the paths of the rotor blades and contact the edges of the opening I6 in the mixing chamber along the surfaces 36 and 3! which again must fit tightly together to prevent leakage of the material from the chamber.

By retracting the surfaces 33 and 34 as compared to prior practice and bringing the upper point 35 to a level considerably below the upper surface of the usual sliding door, and below a plane passing through the rotors, more room is provided above the door to permit the rotor blades to pull inthe stock or batch more easily and offers less obstruction to the charging of the machine through the stack l l by the feed plunger or floating weight. It also subjects the ridge at the upper portion of the sliding closure member to much less wear than has been experienced heretofore, in that this ridge over which the batch is divided is in the present construction with- 4 drawn below the intensive sliding and wearing zone which existed at the upper flat surface of the curved door top. As wear is a function of pressure, friction and movement, it is reduced when a certain amount of the pressure and movement is avoided by lowering the ridge below the point of intense pressure which would exist above it.

While we have shown and described a preferred embodiment of our invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What we claim is:

1. A mixer for heavy plastic materials comprising a doubl cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a bottom discharge opening, a slidably mounted closure member for said opening, the upper sid of said member comprising two plane surfaces meeting at a line substantially centrally of the chamber, and the surfaces sloping upwardly from the side edges of the door to a ridge each of said surfaces on the closure member being substantially tangent to the outline of the adjacent cylinder, and said ridge lying between the blades of the rotor and in a horizontal plane intermediate the plane of the rotors and the lower portion of the cylinders.

2. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a bottom discharge opening, and a movably mounted closure member for saidopening, said member having a sharply defined ridge upon its upper surface and downwardly sloping plane areas on each side of said ridge, said chamber being provided with end walls having lower surfaces fitting snugly against said plane areas, said ridge being parallel tothe axesof the rotors and being disposed between the blades of the rotors and a substantial distance below the plane of said axes, and each of said areas being substantially tangent to the outline of the adjacent cylinder so that an intermediate point of the surface lies closely adjacent either tip of the rotor blade.

CARL F. SCHNUCK. OLIVER W. HOOKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 50,115 Goodwin Sept. 26, 1865 166,181 Barden et a1 Aug. 3, 1875 290,329 Hoifmann Dec. 18, 1883 918,494 Barr Apr. 20, 1909 1,363,230 Clark Dec. 28, 1920 2,351,706 Robinson June 20, 1944 

